Toilet 'sucking'

[bainbrig]

Ground-floor flat. All plumbing usually works well.

Recently, on flushing the toilet, the water seems to be 'sucked' down the u-bend and the usual water level is reduced in the toilet bowl.

What might be happening in the sewers to produce this suction effect, and is it something we should get looked at?

Ta.
BillB

[TheChair]

Sounds like your vent pipe is blocked. The vent pipe allows air to enter the system, thus preventing negative pressure which would cause the water to be sucked out of the waste trap.

[bainbrig]

Thanks Chair. Is that a roof job? (Don’t like heights...)

[klazomaniac]

Do you have an internal air admittance valve fitted ???
If so , this has seized and will need replacing.
If not. The outside stench pipe is blocked as thechair said. It will need rodding by a plumber.

[bainbrig]

Klazo. Not a scooby. As it happens, we’ve got a plumber coming this week to replace a tap, so I think he’ll be our best bet.

[Old_Geezer]

Interesting. When I had an upstairs bedroom converted to a bathroom/toilet the builder said he could remove the top bit of the down pipe as some other method was used these days. Have noticed since then that the water level is often lower than I'd expect.

[bainbrig]

It all still works, but odd. I’ll report back once plumber has given an opinion.

[The Builder]

Syphonage, Bainbrig. The other posts have said it. Air is obviously not getting into the system as it should, to balance the flushing effect.

It'll be apparent to the plumber as to where the problem is.

[bainbrig]

Just to round this one off - we had the plumber in on an unrelated job, and he looked down the manhole and said ‘blocked sewer’.

Phoned Thames Water, midday Saturday, and by 4pm they were there, poking rods down and unblocking it completely.

All free of charge. Amazing level of service, and praise where it’s due.


bB